Solid substrate culture, hydroponic culture and the like are known as soilless culture for growing plants without using soil. Solid substrate culture cultivates plants using growth media as a plant support body, into which a nutrient solution infiltrates. Hydroponic culture cultivates plants with the roots of the plants directly soaked in a nutrient solution. Solid substrate culture includes urethane foam technique, rock wool technique and the like. Hydroponic culture includes deep flow technique, nutrient film technique and the like. In addition, hydroponic culture includes mist culture in which a nutrient solution is supplied to plants by spraying the nutrient solution onto the plants for the purpose of reducing the amount of nutrient solution to be supplied and the amount of water to be used (see PTL1, for example).